1. Field of the Invention
The present invention relates to a contact clip device for establishing a disconnectable electric connection between an omnibus bar of rectangular section, disposed flat or on edge, and a rigid flat conductor placed opposite the bar, in the same plane. It also relates to a current tapping and disconnection block associated with a set of distribution bars for electric switching apparatus and equipped with a plurality of these contact clips.
2. Description of the Prior Art
In connection with a current distribution system having parallel non coplanar omnibus bars, vertical for example, for switching apparatus, it is known to form each current tapping and disconnecting member in the form of a block molded from an insulating material having, on the one hand, a part movable in translation formed by a slide carrying conducting clips clippable on the distribution bars and unclippable therefrom and, on the other hand, a fixed part having conducting knives disposed on edge one of the ends of which is engaged between the two legs of the associated clip and the other end of which is fixed to associated means for connection to switching apparatus; the translational movement of the clip carrying slider is produced under the action of a control member for taking current from the bars and respectively disconnecting it.
Different clip structures of this kind are already known providing a disconnectable electric connection between an omnibus bar and a fixed flat conducting knife situated in the plane of the bar, at a distance therefrom. One of them is formed of two symmetrical flat conducting tongues disposed facing each other; these two tongues are housed and held in position in a through cavity formed in the insulating slider, which is disposed parallel to the bar and to the knife; this clip is further profiled so that in the clipped position one of its ends is engaged on the bar by forcing apart its legs against a resilient clamping force exerted by a compression spring connecting said legs together, whereas its other end is mounted for slidingly bearing against the knife while being subjected to a force exerted by an appropriate clamping member.
To pass from the clipped on position to the disconnected position, the slider is driven in translation so that one of the ends of the clip is separated from the bar by unclipping, whereas its other end held against the knife slides therealong; during this disconnecting movement, the clip moves then in translation over a total travel length which is equal to the sum of its travel for unclipping from the bar and the disconnecting travel properly speaking, this latter corresponding to a given distance separating the clip from the bar and being greater than the unclipping travel distance.
However, this type of double clip providing a disconnectable electric connection has drawbacks. In fact, since during the disconnecting movement, the clip moves in translation whilst slidingly bearing against the fixed knife, appreciable friction forces are therefore created on the knife, over the whole travel distance of the clip; thus, for a high number of clipping/unclipping operations, this pronounced friction results in rapid wear of the knife and damage to the associated contact.